Co-infection with HIV and hepatitis C virus is common in view of the shared routes of transmission of these viruses. Recent data suggests that the course of HCV-related liver disease is accelerated in co-infected individuals. It has also been suggested that infection with genotype 1 HCV may have an adverse effect on HIV disease progression. As the life expectancy of HIV infected individuals increase, hepatitis C infection may be expected to cause increasing morbidity and possibly mortality. Limited data suggests that therapy for hepatitis C is successful in obtaining a response in approximately 22% of HIV/HCV co-infected individuals who have not yet manifested progression to AIDS. At present, the nature of the interaction between HIV and hepatitis C viral infections is unclear. Unfortunately, the lack of a readily available tissue culture system or small animal model for hepatitis C virus precludes a direct examination of this important question. Inferences concerning the biology of coinfection may be drawn from patients harboring both viruses. The dynamics of the interaction between these two viruses may influence the ability to successfully treat hepatitis C. This is a prospective trial of 60 subjects with HIV coenrolled in clinical trials of highly active antiretroviral therapy (HAART) who are naive to HAART at study entry, and are positive for HCV RNA, and who have HIV-1 RNA plasma viral loads of > 2,500 copies/ml. Naivete is defined as never receiving, or receiving for a very limited time, specific active antiretroviral medications that have proven, sustained viral suppression below the limit of detection (500 copies/ml). Highly active antiretroviral therapy is defined as therapy which is likely to result in HIV-1 RNA plasma levels to < 500 copies/ml for at least 16 weeks. During the trial, subjects with confirmed hepatitis C will have plasma collected and evaluated for additional quantitative measurements for HCV by HCV RNA PCR . Subjects will also have plasma collected for HIV-1 RNA levels. The primary objective is to determine the dynamics of hepatitis C viremia in individuals co-infected with HIV who exhibit a reduction in HIV-1 RNA to levels of < 500 copies/ml at 16 weeks of HAART for HIV.